Abstract
For the purpose to investigate the cell-membrane permeability of ^<35>S-thiamine hydrochloride and the outer and the inner portions of ^<35>S-thiamine propyldisulfide (TPD), they were added to human blood in vitro and ^<35>S was traced with the lapse of time. It was found that ^<35>S of thiamine hydrochloride was hardly incorporated into red corpuscles and remained in the blood plasma. In contrast, TPD was immediately incorporated into red corpuscles. ^<35>S (inner) continued to permeate into red cells, on the otherhand, ^<35>S (outer) stayed in red cells only for a time and thereafter it was transfered into the blood plasma. It was revealed that TPD was broken up at the -S-S- bond, leaving thiamine portion in the red cell, the remaining propylmercapto portion was transfered into blood plasma and in this instance, TPD, not being absorbed to the red cell membrane, permeated into the red cell and later it was reduced to thiamine.
